Despite the daily bombardment of shifting and distracting Russia investigation story lines, one that has remained central is the prospect that Robert Mueller will interview Donald Trump. Investigation watchers are atwitter with visions of this heavyweight clash, in which a president who lies shamelessly will face Mueller the truth-seeker and his all-star team with the future of democracy on the line.

In reality, everyone should calm down—because it’s not likely to happen, and that’s probably a good thing for the investigation.

In the end, Trump will not agree to a voluntary interview. Mueller has the authority to subpoena him to appear before the grand jury, but for a variety of strategic reasons should be reluctant to do so. Most significantly, a subpoena would slow things down. Trump and his allies are now racing to undermine the legitimacy of Mueller’s investigation in the hope of muting the impact of its results. The longer the investigation takes, the more successful Trump’s campaign is likely to be. Mueller, therefore, would be well advised to weigh the burden of the time-consuming and distracting litigation that Trump would launch to block a subpoena against the limited value of Trump’s testimony and move on.

Recent weeks have witnessed repeated leaks and speculation about the prospects for a Mueller/Trump sitdown. Trump has said he is eager to talk with Mueller, subject to the advice of his lawyers. His lawyers previously promoted the story that talks to schedule an interview were underway, but more recently word of a split opinion in his legal team has cooled speculation that an interview is imminent.

Indeed, any defense attorney worth his fee would advise Trump strongly against submitting voluntarily to an interview with Mueller. The stakes are high. Trump will not be able to bluster his way through an interview with the very smart and well-prepared Mueller team, and false statements to federal investigators – even if not made under oath – can be felonies.

Past presidents, including Ronald Reagan, Bill Clinton and George W. Bush, have submitted to questioning by independent and special counsels. Reagan answered questions about the Iran/Contra affair while in office and in two depositions after he left. Clinton resisted sitting down with Ken Starr until the independent counsel obtained a subpoena. They then negotiated to allow Clinton to testify for four hours from the White House with his lawyer present and the grand jury connected by video. George W. Bush answered Patrick Fitzgerald’s questions regarding the leak of Valerie Plame’s CIA identity for more than an hour in the White House.

Unlike those presidents, Trump feels no obligation, as head of the executive branch, to support and cooperate with law enforcement. Indeed, he has openly assaulted the FBI, Department of Justice and the very existence of a special counsel investigation. Prior presidents also feared the political damage from appearing uncooperative with law enforcement. Trump has worked furiously to build political support for his resistance to cooperation and appears confident that his base and core supporters in Congress will insulate him from political consequences.

So Trump will almost certainly not agree to a voluntary interview. And Mueller—because of the importance of obtaining spontaneous answers, asking follow-up questions and observing the witness’s demeanor—will not agree to anything less than live questioning. Mueller will then have the option of pursuing a grand jury subpoena for Trump’s testimony. Subpoenas should not be issued lightly to presidents. They are busy people with extremely consequential responsibilities, which include protection of the office of the presidency. Preparing for and delivering grand jury testimony is distracting and time-consuming. Moreover, the precedent set by issuing a subpoena could be abused by less scrupulous prosecutors than Mueller to sully a president for political purposes.

Precedent favors Mueller’s authority to ask the grand jury to subpoena the president. The Supreme Court rejected Nixon’s challenge to the subpoena issued by Archibald Cox for the Watergate tapes. Their production led directly to Nixon’s resignation. Underlying that decision is the principle that no person, including a president, is above the law and no person’s evidence is beyond the reach of a grand jury. That subpoena, however, sought the production of tapes rather than the president’s live testimony. The Supreme Court also rejected Bill Clinton’s contention that Paula Jones’s civil lawsuit could not proceed while he was in office. That case will make it more difficult for Trump to argue that his presidential responsibilities preclude his testimony.

Even though Mueller likely has legal authority to subpoena the president, there are strong strategic considerations weighing against doing so. While investigations cannot be rushed and, particularly in this instance, must be thorough and accurate, Mueller cannot afford delay. Attacks on the legitimacy of the investigation by Trump, his congressional supporters and his allies in the right-wing media increase daily and threaten to blunt the force of Mueller’s findings. Trump will respond to a grand jury subpoena with a protracted legal challenge that will go to the Supreme Court. At the very least, he is likely to challenge the constitutionality of the special counsel’s appointment; argue that Mueller has exceeded his authority by investigating tangential matters; urge the court to impose limits on the scope, time, place and manner of the questioning; and contend that much of the information the grand jury will seek is covered by executive privilege. Mueller is likely to prevail, but victory will take time and distract his team from wrapping up the investigation, while giving Trump endless opportunities to denounce the “witch hunt.”

At this stage, Trump likely fits the U.S. Attorney Manual definition of a “target,” as a person against whom there is “substantial evidence linking him or her to the commission of a crime and who, in the judgment of the prosecutor, is a putative defendant.” According to Justice Department policy, a prosecutor may request a subpoena for a target only with the authorization of a high-level supervisor and after considering (1) the importance of the testimony, (2) whether the information can be obtained by other sources and (3) whether the testimony might be protected by privilege.

None of these factors strongly supports a Trump interview. It seems unlikely his testimony would advance the investigation significantly. Mueller has substantial information from other sources and from Trump’s intemperate and revealing tweets and public statements. Trump’s contempt for truth could engender false statement crimes, but that possibility alone is not a reason to haul him in. Those crimes can provide important leverage to force cooperation by lesser players, such as George Papadopoulos and Michael Flynn, but without an underlying crime they will not support action against Trump. Despite the Nixon precedent, Trump may assert executive privilege regarding his conversations with aides. And, of course, he can assert the Fifth Amendment in refusing to answer any question that might incriminate him. Although taking the Fifth could be politically embarrassing, grand jury secrecy might prevent the public from learning of it.

A prosecutor who does not intend to seek a subpoena should still offer a target the option of a voluntary appearance. Mueller, therefore, consistent with Justice Department practice and in the interest of speedy completion of the investigation, should send Trump an invitation letter, but when Trump refuses to testify, should not ask the grand jury to follow with a subpoena. That’s unlikely to satisfy those rooting for an epic showdown between the prosecutor and the president, but it’s the smart thing for Mueller to do.